McKenna received his Master's degree in botany at the University of Hawaii in 1979. He received his Doctorate in Botanical Sciences in 1984 from the University of British Columbia, where he wrote a dissertation entitled Monoamine oxidase inhibitors in Amazonian hallucinogenic plants: ethnobotanical, phytochemical, and pharmacological investigations.
McKenna's research led to the development of natural products for Aveda Corporation as well as greater awareness of natural products and medicines. He has authored numerous scientific articles and books. He co-authored The Invisible Landscape with his brother Terence and Botanical Medicines: the Desk Reference for Major Herbal Supplements with Kenneth Jones and Kerry Hughes. McKenna spent a number of years as a senior lecturer for the Center for Spirituality and Healing, part of the Academic Health Center at the University of Minnesota, Twin Cities. He is now a senior research scientist for the Natural Health Products Research Group at the British Columbia Institute of Technology in the Vancouver area.
His research has included the pharmacology, botany, and chemistry of ayahuasca and oo-koo-hé, the subjects of his master's thesis. He has also conducted extensive fieldwork in the Peruvian, Colombian, and Brazilian Amazon.
McKenna's memoir, The Brotherhood of the Screaming Abyss about his and his brother Terence's life and journeys together, was published in 2012.
He is featured in the documentary "DMT: The Spirit Molecule".
McKenna participated in the first Evolver Convergence 2012 in Pittsburgh, June 1–4.
Main guest several times on popular radio show Coast to Coast AM. His last appearance on the show was the November 25, 2012 episode.
- Heffter Research Institute, biography and publications
- Erowid's Dennis McKenna Vault
- She Who Remembers Audio Archives of Terrence and Dennis McKenna interviews (MP3s).
- Biography page for the Center for Spirituality and Healing
- 2009 – Cognition Factor (2009)